LOS ANGELES (Reuters) - Brought back from the brink of financial ruin by a philanthropist's $30 million gift, the Museum of Contemporary Art in Los Angeles celebrates its turnaround this weekend with the most ambitious exhibition of its own iconic collection.

More than 500 works by the likes of Piet Mondrian, Mark Rothko, Jackson Pollock, Jeff Koons and Jean-Michel Basquiat have been selected from MOCA's 6,000 works, considered one of the world's top collections of post-World War II art.

"MOCA's First Thirty Years" marks the museum's 30th anniversary -- a milestone that might not have happened had Eli Broad not come to the rescue.

Many U.S. museums have fallen on tough times in the worst economic downturn in decades, some forced to sell works to survive.

"We were among the first institutions to be hit very hard and very early and we are among the first to be saved in this process," said MOCA chief curator Paul Schimmel.

Broad, a renowned modern art collector and philanthropist who created KB Home homebuilders, offered $30 million to get MOCA out of financial straits if others came forward. In just 10 months, an additional $30 million was raised.

"This is the biggest turnaround of any art institution, whether it is performing arts or the visual arts, if you think of all that has happened in the last year," Broad said Thursday as he admired a 1939 Mondrian, MOCA's earliest work.

Whereas a year ago, there was talk that MOCA would be merged with another museum or even closed after its budget went well beyond annual income, it has now balanced its budget, eliminated debt and begun the search for a new director.

AMBITIOUS EXHIBITIONS AHEAD

Warhol Foundation President Joel Wachs, who sits on MOCA's advisory board, said the comeback, while impressive, is "not yet complete."

"It can't rest on its laurels and it can't rely on a very few people to rescue it," said Wachs, adding that MOCA must continue "the kind of exhibitions it has become known for."

Indeed, MOCA's exhibitions with art from around the world have won national and international praise, like the recent retrospective of the work of Takashi Murakami.

Broad wants MOCA's own works -- including what he calls the best Rothkos of any museum -- to be more visible. But he also prizes the exhibition legacy and gave half his gift -- $15 million or $3 million a year -- to fund exhibitions.

Schimmel, MOCA's chief curator since 1990, said he is working with "smaller budgets and more restricted financial landscape," like most art institutions these days.

The big test for MOCA, he said, will be to remain true to its core ideals of being an influential and cutting-edge museum in the new financial landscape.

The MOCA exhibition to run November 15 to May 3 is split between the museum in downtown Los Angeles, where the earlier works are shown, and a second nearby MOCA venue The Geffen Contemporary, which shut for 10 months due to the cash crunch.

Apart from eight Rothkos in a single gallery, visitors can enter Ed Ruscha's Chocolate Room made of chocolate on paper and smelling like chocolate. Or, if they remove their shoes, they can wander into an all-white and neon room by Doug Wheeler.

Kicking it all off is a gala for 1,000 guests on Saturday night, where Italian artist Francesco Vezzoli will set the stage for a performance starring Lady Gaga and the Bolshoi Ballet. MOCA expects it to bring in another $3.5 million.